The present invention relates to a device for prevention of ulcers in the feet of diabetes patients and, more particularly, to such type of device that functions to detect and signal to the patient presence of adverse pressure and temperature conditions affecting the feet.
In severe forms of diabetes, a diabetes patient can suffer a partial or complete loss of feeling in the lower extremities and especially in the feet. Commonly, the patient fails to notice or be made aware when individual points of a foot are subjected to severe constant pressure condition, for example during long periods of standing. Prolongation and repetition of that condition can lead to development of pressure sores and open wounds, which can become inflamed and easily ulcerated. In addition, small sharp objects can enter a shoe and present a danger of cutting the patients feet without any indication to the patient because of the partial or complete loss of feeling in the feet. Since metabolism and blood circulation already are reduced in diabetes patients, healing of such sores is most difficult. Therapy for dealing with the sores depends on the severity of a wound and the patient's blood circulation condition. But generally, therapy will dictate that a patient's feet be exposed to as little stress as possible and that the patient be aware of the exposure so that the condition be removed.
Therapy also includes prevention of pressure sores and wounds so that a patient who might not be able to recognize existence of a severe sore inducing condition can get off his or her feet to eliminate the condition and reduce the risk of onset of sore development.
Devices are known in the prior art for indicating to a diabetes patient that their feet are being exposed to an excessive stress condition.
U.S. Pat. No. 4,647,918 discloses a shoe insert which is provided with a number of pressure sensors connected by cables with an evaluation device, the evaluation device measuring stress periods and values and making evaluation of these according to prescribed requirements. The device gives discernible warning to a patient but the device is complex and expensive so that its use is limited to a small group of patients.
U.S. Pat. No. 4,813,436 discloses a system for analyzing a person's walking gait. The system includes use of sensors in an inner sole that are connected to processor apparatus so that pressures to which a person's foot is exposed during walking or running can be recorded.
U.S. Pat. No. 5,042,504 discloses a device for monitoring loads imposed on a human body, such monitoring including of the feet. Sensors placed under the sole of a person are used to acquire data, via microprocessing, regarding loadings placed on the feet, this data being recorded to provide a history of the loadings etc that is useful to a physician who may be treating a patient's feet disorder.
European Published Application EP 0 136 247 discloses a device wherein a number of liquid cells are arranged below the sole of a foot inside a shoe, these being connected with tubes to a sleeve wrappable about a person's calf below the knee. When pressure is brought to bear on the liquid cells, i.e., when a patient is standing, pressure at the foot is communicated to the calf to cause uncomfortable feeling there and, hence, signal to the person of the undesirable foot pressure condition. The device is quite expensive and requires use of special shoes.
While these devices can sense and signal an adverse pressure condition to a patient, they are limited to that function only. Another and equally important condition to which a diabetes patient's feet can be exposed and which a lack of knowledge by the patient can be detrimental to foot well being is temperature. None of the above prior art devices disclose means which sense temperature. If fact, this prior art does not treat of the need for sensing foot temperature as a concern in respect of therapy for treating the feet of diabetes patients.
The significance of signalling a patient as to a foot temperature is that above normal temperature can mean infection, inflammation or analogous symptom indicative of need for remedial action. Where the temperature is low, it could be a sign of frostbite, an occurrence easily brought about by a patients presence in an outside environment of severe cold. Since many diabetes patients lack feeling in their feet, they cannot feel the manifestations in the feet given by the frostbite as such.
Accordingly, it is desirable that there be provided a device which functions to warn a diabetes patient of both adverse pressure and temperature conditions affecting his or her feet.